As the application of inertial measurement devices, such as Micro-Electromechanical Sensor (MEMS) accelerometers and gyroscopes expands into areas that have not been exploited before, e.g. wearable technology, Internet access devices, navigation devices, etc., the form-factor of such devices becomes a critical metric in designing the sensor element. This metric brings about an inevitable reduction in proof-mass size, which results in smaller device sensitivity, requiring higher gain analog front-ends. However, non-ideal capacitance mismatches in a differential accelerometer (CP-CN) caused by process variation or package parasitic, are also amplified by the increased gain, which, if left uncompensated, can create a large offset voltage at the output, thereby deteriorating the system performance. When size of the sensor scales down, its impact on system performance can be even greater as parasitic capacitances are not affected by such scaling.
A MEMS accelerometer interface circuit can be used to converts the capacitance change caused by the acceleration, into the electrical signal, However, if there is any mismatch between MEMS capacitors, it will result in a huge offset, or temperature dependent variation that would deteriorate sensor performance.
Accordingly, a need exists for calibration circuitry in MEMS accelerometer interface circuit that can be used to address mismatch between MEMS capacitors.